| 摘要 |
A mast structure for a storage and retrieval machine is disclosed which includes first and second vertical members having lengths affixed to each other. The second vertical member includes a plate extending along the length of the second vertical member and spaced from the first vertical member in the direction of the path of travel of a base of the storage and retrieval machine. The first and second vertical members respectively have cross-section areas perpendicular to their lengths which are substantially equal to each other. The first and second vertical members together have a physical center and a centroidal axis both extending along the length of the members which may be adjacent to each other and preferably coincide with each other so that the two members together have a maximum section modulus in the direction of the path of movement of the base. The first vertical member has a tubular cross-section shape for guiding a carriage of the storage and retrieval machine along the length of the mass structure which is of a rectangular shape. The second vertical member is tapered so that the cross-section area of the second vertical member decreases in an upward direction to decrease the section modulus of the mast structure at its upper end where impact loading is less.
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